When a rider performs an operation to close a throttle of an engine while traveling in a leisure vehicle, for example, a motorcycle, in which a four-cycle engine is mounted as a power unit to drive the leisure vehicle, a negative drive force (braking torque) is generated in the engine to cause engine braking. As a result, the motorcycle decelerates.
The engine braking is able to assist a brake device to stop the motorcycle smoothly or to decelerate it at a suitable speed near a corner.
In these cases, to enable the engine braking to occur in a suitable condition, the rider selects a gear position for effecting the engine braking according to a travel speed, and operates a clutch lever slowly.
In order to enable the engine braking to occur optimally, it is required to effectively utilize an engine braking characteristic or the like of the motorcycle according to the travel speed. When a higher gear position is selected instead of an optimal gear position to effect the engine braking, desired deceleration or engine braking may be difficult to achieve, while when a lower gear position is selected, greater engine braking tends to occur.
In order to solve the above mentioned problem, Japanese Laid-Open Patent Application Publication No. Hei. 10-159594 discloses a motorcycle capable of achieving suitable engine braking.